JPS6136113A - Circulation manufacture and device for silicon molded shape - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention consists in transporting the mold sequentially from a supply section to a casting section, filling it with molten silicon, transferring it to a cooling section after directional solidification of the silicon has taken place, and finally removing it. The present invention relates to a method and apparatus for the cyclical production of a silicon molded body having a columnar structure, which is composed of a single-crystal crystal zone having a crystallographically desirable orientation.

Polycrystalline silicon, which has a columnar structure consisting of single-crystalline bands with favorable crystallographic orientation, is becoming increasingly attractive as a solar cell substrate and as a means of generating electricity using photovoltaic techniques, which can compete with conventional energy carriers. It is considered important. This material, which is known from DE 25 08 803, can be produced according to DE 2 745 247 using the bovine continuous casting method.

In this method, molten silicon poured into a mold in the casting section is subjected to a vertical temperature gradient of 200 to 1000 DEG C., resulting in hardening. When the silicon is completely solidified, the mold is further cooled in the cooling section, and after this cooling, it is taken out. During this time, another mold is transported from the supply section to the casting section and filled with molten silicon. Although this method is effective in itself, it requires fairly expensive heated fabrication of the casting in order to adjust the temperature gradients in the mold. Furthermore, since the casting section is completely isolated from other steps during the entire solidification process, the production rate of equipment operated by this method can only increase to a rate determined by the solidification rate of the silicon. Guy.

Starting from this state of the art, the object of the present invention is to provide a method which makes it possible to circularly cast silicon shaped bodies having a columnar structure with low equipment costs and high production rates.

Each mold entering the casting section from the supply section is heated to a temperature of 20° to 1550°C before supplying molten silicon, and after filling with molten silicon, the mold is crystallized before the silicon solidifies. the silicon undergoes directional solidification by directional energy removal, and during this solidification the free surface of the silicon is maintained at least partially in a molten state until the end of the solidification process; The problem is solved by a method characterized in that the mold is transferred to a cooling section after the silicon has completely solidified.

The device for carrying out this method is characterized by:
i.e. an evacuable, vacuum-tight casting part containing a melting crucible surrounded by a heating device and from which silicon can be removed, at least one part communicating with the melting crucible separated from the outside air by a vacuum-tight isolation device. A casting section having a charging channel and a mold holder for moving the mold into the casting position; an energy source for supplying energy to the exposed silicon surfaces in the mold; and an energy source facing the energy source. at least one crystallization section connected to the casting section, having a removal device; at least one supply section communicating with the casting section, but separated from the casting section by a vacuum-tight shutoff device; moving the mold to the desired section; It is characterized in that it consists of a conveying means i and gas supply and discharge pipes.

The method and apparatus will be explained in more detail in connection with FIGS. 1 and 2: similar features in both figures are given the same reference symbols.

The mold 1 used in this method (shown only diagrammatically in the drawing) is known in principle from the first-mentioned patent documents. The mold is generally a hollow body, preferably open on one side, with a preferably rectangular internal cross-section, made of a silicon-stable material, such as graphite, silicon nitride or silicon carbide. , the size of which is determined by the amount of molten silicon to be accommodated. This internal size is selected in such a way that, after optional edging, a molded body is obtained from the solidified silicon with a rectangular or square cross section with a side length of 100 to 1100 cm, preferably 600 to 500 cm. The target height of the product is 15
It is desirable that it is 0-250g. For example, silicon, silicon carbide, silicon nitride,
It has also proven useful to provide a lining or coating of graphite, quartz or other suitable ceramic materials. Molds are particularly advantageously used in which when energy is supplied through the aperture, energy is essentially released from the interface corresponding to the aperture. For example, it is desirable that the sides of a hollow cylindrical mold have better thermal insulation properties than the bottom surface.

In the method according to the invention, each empty mold to be filled is inserted into a feed section 2 which is preferably divided into two parts, ie into an insertion section 3 and a preheating section 4 . The mold first enters the insert 6 at the very end, where the air is evacuated and a suitable working pressure is established, usually from 10-3 to 10-3, optionally by mixing with an inert gas or inert gas mixture. adjusted between mbar,
It is then transferred from the insert 6 to the preheating section 4, which is separated by a shut-off element 5, for example a vacuum slide valve. The mold 1 is now brought to the desired temperature for the casting process. That is, first pre-drying at about 150° to 350°C, then drying at about 5°C.
~300°~2000°C, preferably 1500°C
Heating at ~1300°C removes remaining volatile impurities. This process can be carried out under vacuum or with hydrogen, for example.
Preferably, it is carried out under a nitrogen blanket or an inert gas such as argon. The mold is then brought to the actual working temperature of 20° to 1550°C, preferably 850° to 1650°C. In this case, it is desirable to cool the silicon at a particularly selective rate, mainly in the low temperature range of 20 DEG to 850 DEG C., and it is effective to use a mold made of a material that can sufficiently withstand temperature shocks.

For example, by firing from 1500° to 1700°C (
(e.g. according to DE 29 56 164 A1) or in order to carry out an additional refining action by particularly effective segregation of impurities in the direction of the molten surface during the crystallization process, the cast silicon is brought to a completely molten state. A mold temperature of 1650° C. or above, especially a mold height above the melting point of silicon, is desirable when it is to be maintained. In such cases, it is generally necessary to use a mold made of a particularly stable material, such as silicon nitride, or at least lined or coated with such a material. For preheating and heating, the use of radiant heating elements advantageously arranged on the mold, preferably made of graphite or silicon carbide, has proven effective, but other heating methods, e.g. Alternatively, the use of induction heating methods is also conceivable in principle.

After preheating, the mold is transferred from the feed section 2 to the casting section 7, which is separated from this section by a shut-off element, for example a vacuum valve 6, so that the same pressure conditions prevail inside during this transfer operation. The casting section 7 has a melting crucible 8 . This melting crucible is usually in the form of a hollow cylinder, preferably located above the mold and, according to a preferred embodiment of the invention, tiltable in order to release the molten silicon 9 by pouring. This molten crucible Ir made from a silicon-stable material, preferably silicon, is preferably heated directly using a heating device provided inside the casting section 7, but it is preferably heated directly using a heating device provided inside the casting section 7. It is also desirable that the material be heated by induction using a second heating element preferably made of graphite. This second crucible is also tiltable, with a part of it being 1
A book or more is placed inside the induction coil. In order to minimize heat losses, it is advantageous to insert one or more electrically insulating and thermally insulating layers of about 10 to 2004 mm between the heating lamp and the coil.

The melting crucible is preferably insulated from above and/or by means of a tiltable insulation layer or a radiator, made for example from suitably heated graphite or silicon carbide plates, which can be removed during charging or casting. Alternatively, it is possible to optionally insulate or heat from below.

To facilitate the replacement of used melting crucibles, which is sometimes necessary, it has proven effective to provide heating crucibles with conical side walls that widen upward from the bottom and a vertically movable bottom. . Preferably, the storage area has its own vacuum-tight access means for installing and removing the melting crucible on its outer wall.

Usually granular to agglomerated (average particle size typically between about 1 and
150 mm), the silicon to be charged is fed into the molten melt through the charging channel. A charging channel, usually duct-like, leads from the gate of the reservoir for supplying the material to be melted from the outside into the casting section to a position suitable for filling the crucible above the opening.

The charging channel is optionally oscillatory and duct-like, ie it is movable and can be moved from an active position during filling to a rest position during the melting process. The charging channel can also have conveying means for conveying the material charged outside the casting section, to be fed via the gate to the melting crucible, and for discharge at the gate.

In this connection, it has been found to be advantageous not to fill the molten melt in one step, but to gradually fill it in small quantities. This means that the charging channel can be made smaller and at the same time a high degree of filling of the melting crucible is obtained.

If the silicon is already obtained as melt from a pre-purification step, for example according to DE 29 33 164 or DE 2 729 464, it is also possible to feed the silicon in molten state to the melting point. In principle it is possible.

In such a case, consideration may be given to filling the mold directly, ie, without intervening a melting melt.

When charging solid silicon, 150 ml of molten Ruho
It is desirable to maintain a temperature between 1300°C and 1300°C.

In the case of quartz melting crucibles, it is advisable to choose a temperature between 700° and 1500°C. This is because experience has shown that in this temperature range the material has relatively desirable properties in terms of resistance to mechanical stress. When adding the charge to an already existing melt, i.e. to molten silicon, the feed rate should be adjusted in such a way as to avoid solidification of the entire contents of the crucible. It has proven advantageous to regulate the temperature, otherwise the crucible wall would be exposed to high mechanical stresses due to the volume increase of the silicon during solidification.

A dopant can also be added as necessary when recharging.

Generally, during the melting process the casting part is 0.1-100mb
ar, preferably a pressure of 1-2 D mbar. It is particularly advantageous to feed the inert gas from above towards the surface of the melt.

When or just before the material in the melting crucible is completely molten, the mold 1 is transferred from the supply section 2 to the casting section 7, where the mold receiver is placed on a platform 10 and then filled with molten silicon. To avoid too long casting distances, the mold is generally placed close to where the molten silicon 9 is discharged from the melting crucible 8.

For this purpose, a preferably rotatable shaft of the container with a suitable support surface is provided so that the mold can be raised and lowered. This means that in most cases it is not necessary to use additional means during the casting process, such as for example holes or ducts.

It is advantageous to rotate the casting mold on a central longitudinal shaft, preferably at a speed of about 10 to 60 revolutions per minute. In this way, the thermal and mechanical stresses to which the mold is subjected can be reduced. At the same time, a solid silicon layer 12 forms within a short period of time at the interface between the mold wall and the silicon melt, so that the remaining molten silicon in the mold is, as it were, surrounded by a crucible of solid silicon. Become. This serves in particular to reduce the risk of impurities being formed by reactions between the melt and the silicon melt.

In order to avoid overheating of the mold by the hot melt when pouring it, a so-called sacrificial piece can be used, for example, as a lining of the mold, according to the ice cube principle. These sacrificial pieces melt themselves and carry away heat from the melt.

When the molten silicon is injected and before it completely solidifies, the mold is removed from the mold base 10 and the crystallized part 11 is removed.
Move to. The most suitable moment for this work is when a complete crust of solidified silicon has formed on the surface of the melt as a result of high thermal radiation. This crust prevents spillage of the melt during transportation and protects the melt from impurities.

In the crystallization zone 11, at least a portion of this crust formed from the silicon itself is redissolved; a complete redissolution of the already solidified silicon 12 is not necessary in most cases. As energy source it is preferred to use a radiant heat source, for example as a graphite or silicon carbide heating element.

It is placed above the mold aperture and radiates energy onto the exposed surface of the silicon. It is of course also possible to heat the silicon surface using force heating methods, for example resistance heating or induction heating.

The heating element is desirably maintained at a temperature above the melting point of silicon up to about 1300°C, preferably between 1460° and 1480°C. To create a nearly vertical energy flow, the mold face or bottom face facing one energy source is given the opportunity to release energy, resulting in a temperature gradient. This can be done, for example, by heat radiation or heat exchange using heat exchange surfaces made of graphite, copper or iron in contact with the mold bottom, through which a liquid or gaseous coolant flows. For example, the energy removal by cooling using cooling water is preferably adjusted so that the energy supply is such that a crystallization rate D of 1 to 5 per minute, particularly 1 to 2 per minute is obtained. As previously discussed, the development of nearly horizontal crystallization planes can be promoted by insulating the sides of the mold.

During crystallization, the total silicon is mostly, i.e. about 80-95
A heater is used to maintain at least a portion of the exposed silicon in a molten state until the silicon solidifies. The temperature of the heating element is then gradually increased, preferably from 0.1 to b, so that the silicon on the exposed surfaces of the mold begins to gradually solidify. This method is characterized in that during the solidification process the molten silicon is encapsulated by the solidified silicon and thermally induced stress in the product and/or mold as a result of the volume increase during solidification.
Prevent cracks or other mechanical damage from occurring.

By rotating the mold around its vertical axis,
It is also possible to have a desired influence on crystallization.

During crystallization, a vacuum or inert gas atmosphere of preferably about 5 to 100 mbar is maintained in the crystallization section.

It has proven particularly advantageous to pass a stream of inert gas over the melt surface to remove any gaseous impurities, such as silicon or carbon monoxide, which may occur.

When the silicon is completely solidified, a tempering process is applied to the silicon to reduce the stress in the material and at the same time to homogenize the temperature distribution. In principle, this step could also be carried out in the crystallization section 11, but it is more advantageous to transfer the mold to the cooling section 16, which is connected to the crystallization section 11.

This cooling section is preferably divided into two sections: a tempering section 14 and a quenching section 15. The mold first enters the tempering section 14. A blocking element between the tempering section 14 and the crystallization section 11 is generally not necessary. The solidified silicon 12 is then tempered to a temperature of 900° to 1300° C., preferably at a cooling rate of 0.5° to 30° C./min. During this stage, the silicon in the mold is generally no longer cooled from the bottom and the energy radiated to the exposed surfaces of the silicon is reduced by about 10-50% of the value used in the crystallization section.

As in the crystallization section, energy is supplied from any suitable heat source, such as, for example, a resistive or inductive heating system, but preferably by a radiant heater, for example consisting of a graphite or silicon carbide heating element.

When the required temperature is reached, the temperature is monitored throughout the apparatus, preferably using a non-contact temperature measuring instrument, such as a pyrometer.The mold is further transferred to the quenching section 15. This quenching section is separated from the tempering section 14 by a vacuum-tight barrier element 16. The solidified silicon is now at the pressure and temperature conditions under which it will ultimately be released from this section. Temperatures below 700° C. have been demonstrated to be suitable for releasing silicon. The first reason is that this temperature is within the temperature range in which silicon can be plastically deformed.
The second reason is that the temperature is outside the range of 0° to 900°C.If oxidizing gas (e.g., air) enters graphite auxiliary equipment, such as a mold, there is a danger that the equipment will catch fire. The reason is that the temperature is small at this temperature. Preferably, the cooling is carried out using a non-oxidizing ZR gas flow, especially a nitrogen or Alzan flow. This gas stream flows over the mold and optionally circulates within the vessel and is cooled externally. Furthermore, the cooling effect is enhanced by the heat exchange surface in contact with the mold bottom, through which the coolant flows. The pressure in the quenching section, which is adjusted to be approximately the same as the pressure in the tempering section when the tempered mold is charged, can be increased by atmospheric pressure at the start of the quenching operation. In principle, the tempering step and the quenching step can be carried out in one section, but in this case a vacuum-tight element is essential, which isolates this section from the crystallization section. When the temperature limit of 700°C is reached, the quenching section can be ventilated.

According to the embodiment shown in FIG. 2, a melting crucible 8 with a tiltable charging unit is provided in the vessel apparatus for carrying out the method according to the invention, and a turntable is provided in the plane below the melting box. In the mold receiver arranged as shown in FIG. ing. The casting tower 17 is connected to a charging/discharging line 19 by a supply/discharging gate 18 . The mold 1 first enters the insert 6 and then into the transfer part 21 which is separated from the insert by a vacuum-tight blocking element 20 . From here, on the one hand, empty molds can be fed to the casting tower 17;
On the other hand, the mold filled with solidified silicon and discharged from the casting tower is conveyed further to the quenching section 15 . In the case of an empty mold, the moving part 21 performs the work of the preheating part (according to FIG. 1), ie heating and establishing the working temperature and pressure. On the other hand, the filled mold is generally conveyed as quickly as possible to the quenching section, so that this mold does not block the transfer section with respect to the empty mold to be heated.

The molds can be fed into or discharged from the casting tower 17 by means of horizontally moving sliding forks 22, for example. The supplied empty mold enters the mold holder 10 and is placed at a location 1 where molten silicon 9 is ejected from the melting crucible 8, usually by a rotatable shaft of the holder, similar to the method described in FIG. Rise. When the mold is filled, it is returned to its starting position and then transported to the next rotatable position, i.e. the crystallization section, where the silicon, present at any time from the previous casting process, undergoes directional solidification. The mold, already filled with fully solidified silicon 12, is simultaneously transferred by a rotary movement to a tempering section 14, which contains silicon already tempered to a temperature of 900° C. to 1700° C. The mold reaches the mold holder 10 and is discharged from there to a moving section 21 and then to a quenching section 15. After a new, suitably prepared empty mold has passed through the transfer station 21, the empty mold receiver in the casting tower can occupy the platform 10.

The apparatus for carrying out the method according to the invention, which is shown in FIGS. 1 and 2, can of course be modified in many respects, departing from the idea of the invention. This is especially true for machines with several parts working in parallel or in succession, for the most time-consuming and therefore determining process of production rate. For example, embodiments with several feed sections, crystallization sections, tempering sections or rapid cooling are also possible. In this connection, the fact that the casting and crystallization steps are not closely coupled also has advantageous consequences.

A particular advantage of this method is that all parts can be occupied by the mold at the same time and that the steps can be carried out in parallel. A preferred embodiment of the invention includes the following steps which may be carried out simultaneously: inserting a new mold into the insert while the solid silicon charged in the melting crucible is melting; Heat the other molds in the preheating section.At the same time,
In the crystallization part there is a mold containing solidified silicon, in the tempering part there is a mold whose contents have been tempered to about 900°C to 1300°C, and in the quenching part, the tempered silicon is Other templates containing the template are conditioned for release. When this last-mentioned mold is discharged from the device, all molds vacate their previously occupied positions and move to the next section. The heated mold is transported from the preheating section to the mold holder, during which it is filled with molten silicon, and then enters the crystallization section, where the mold that previously occupied the crystallization section is moved to the tempering section. It will be done. While crystallization is taking place, new silicon is melted in the melting crucible. During this process, the mold holder must be emptied in the arrangement according to FIG. 2, but is occupied by the mold in the arrangement according to FIG.

However, in principle, this preferred simultaneous occupancy of parts does not necessarily have to be realized.

In order to transfer the mold to the destination, consideration can be given to the known conveyance means for this purpose, which are familiar to the person skilled in the art.

For example, conveying slides, sliding forks or, in many cases, rotating platforms can be used. A suitable solution is the use of individually controllable rollers.
This is the use of lines. This roller line is activated as needed to allow the desired movement of the particular mold selected. The use of conveyor belts is less desirable because it requires the processes to be carried out in precise synchronization.

The silicon blocks obtained by the method of the invention have a columnar structure consisting of a single crystalline zone with a crystallographically preferred orientation, with 0. °~100+mn, typically 1~
It is usually possible to obtain an average particle size of 60 pieces. When the edges are removed, this block constitutes an excellent solar cell substrate with efficiencies on the order of 10-17 inches.

EXAMPLE In an apparatus corresponding to FIG. 2, a silicon lump is placed in a tiltable, induction-heated quartz melting crucible (height: about 60 Dtan, diameter: about 500+ nm, wall thickness: about 8 mm) in a casting tower with water-cooled refined steel walls. (particle size approx. 5-150 mm) was added gradually in small portions (approx. 5-20 in 9 increments) by means of a charging channel with a tiltable shovel mechanism until it was almost completely filled. After this charge had partially melted, additional silicon was added in small portions (approximately 5 to 20 increments) until a total of approximately 100 silicon had been melted. During this melting process, the crucible was maintained at a temperature range of approximately 1420° to 1480°C, ultimately reaching a melting temperature of 1460°C (measured by pyrometer). The pressure inside the container with the argon flow flowing downward is 10
It was mbar.

At the same time, a hollow graphite cylinder (with an internal height of about 280 m
A sea bream (inner edge length approximately 430 m, outer diameter including side wall insulation approximately 750+ nm) was pushed into the insertion section of the charging/discharging line, which was isolated from the outside air by a vacuum-tight flap. When air is removed and working pressure is established (approximately 1
0-1 to 10-3 mbar), the mold was further conveyed by means of a conveying slide to the moving part of the charging and discharging line. This section has already been purged of air and separated from the insertion section by a water-cooled vacuum valve.

Using a heated graphite radiation heating plate placed above the mold and having a shape corresponding to the cross section of the mold, the mold was maintained at about 250° C. for about 60 minutes and vacuum dried. The temperature of the heating element was then increased to approximately 1500°C and the mold was heated for an additional 60 minutes. The temperature of the mold is then lowered to about 1100°C and the temperature is reduced to about 10 m
An argon pressure of bar was established.

The silicon charged in the melting crucible completely melted during this time. At this point, the mold was further transported from the moving section to the mold holder of the casting tower by a sliding fork.

This receiver, a graphite pan with additional gas insulation, connected to a water-cooled insert rotating shaft, moved the platform upward until the desired casting position was reached. The melting crucible was then tilted and the molten silicon was forced into the mold which was rotating at approximately 10 revolutions per minute.

When the mold is completely filled, the melting crucible can be returned to its initial position and reloaded with solid silicon. While the mold was still rotating, it was moved back from the injection position and the mold holder remained in the bench until the surface of the injected silicon was coated with a thin layer of solidified silicon. Once the silicon surface was covered with a solidified silicon layer, the mold was transferred to the crystallization section by means of a rotating table.

Here, the exposed surface of the silicon was again completely melted from above using a graphite radiant heater (temperature of about 1440° C.), and the bottom of the mold was cooled by a water-cooled copper plate. The silicon melt at a depth of about 215 was completely crystallized after about 240 minutes at a crystallization rate of about 1.0111 I+I/min. Toward the end of the crystallization process, when about 90% of the silicon present had solidified, the temperature of the radiant heater was reduced at a rate of about 0.5' until the exposed silicon surfaces had also solidified. During the crystallization, the mold was rotated at approximately 10 revolutions/min and in the final stage at approximately 1 revolution/min. at the same time,
A light stream of argon was passed over the silicon surface.

The mold containing fully solidified silicon was then further transported to the tempering position using a turntable and left there until the bottom was no longer cooled.

The temperature of a radiant heater set just above the opening of the mold was lowered at a rate of about 2.5°C/min from the initially set value to 1260°C, corresponding to the final temperature of the crystallization zone. ℃ and then the heater was turned off completely. After about 90 minutes, the temperature within the mold had dropped to about 950° C., and the temperature distribution was generally uniform.

At this time, the mold could be removed from the casting section.

For this purpose, the mold, in particular the mold holder, is transferred to a stand using a rotary table, from there it is transferred using a sliding fork to a transfer section, and from there it is loaded and loaded using a transport slide.
It was transported directly to the quenching section of the unloading line. The cooling section was filled with a flow of argon and adjusted to atmospheric pressure. The argon atmosphere was constantly circulated and cooled by an external heat exchanger. As a result, (2B) the temperature was lowered to below 700° C. within about 150 minutes. Next, the cooling device was turned off and the quenching section was opened. The mold was removed and the silicon block was removed after a final further cooling in air.

Saw the resulting block upwards to form a 10x10c
Individual blocks with a cross section of rn were obtained which were then divided into wafers used as the actual starting material for solar cells. The solar cells obtained from this are 10-16
% efficiency.

By simultaneously occupying the insertion section, the transfer section (as a preheating section), the crystallization section and the quenching section with an empty or filled mold, and simultaneously melting the silicon in the melting crucible, the finished silicon block is removed from the device every 4 hours. The process could be carried out such that the mold containing the mold could be removed. The residence time in each part was adjusted to the most time consuming step, usually the melting or crystallization step.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a possible embodiment of manufacture for carrying out the method of the invention, and FIG. 2 illustrates another possible embodiment of such a device. 1... Mold 9... Molten silicon 2...
Supply section 10...Mold holder is stand 7...Casting section
11...Crystallization part 8...Melting melting point

Claims (1)

[Scope of Claims] 1) A crystallization method comprising: 1) transporting molds one after another from a supply section to a casting section, filling them with molten silicon, transferring them to a cooling section after directional solidification of the silicon has taken place, and finally removing the molds. In a process for the cyclical production of columnar structured silicon bodies consisting of single-crystal crystalline zones with a scientifically preferred orientation, each mold entering the casting section from the feed section is heated for 20 minutes before being injected with molten silicon.
° ~ 1550 ° C., after the mold is filled with silicon and before the silicon is completely solidified, the mold is transferred to the crystallization section,
Here, the silicon undergoes directional solidification due to the release of directional energy, and during this solidification, the exposed surface of the silicon is maintained at least partially in a molten state by the energy supply until the solidification process is completed, and the silicon is crystallized. A method characterized by transporting the mold to a cooling section after the silicon has completely solidified in the cooling section. 2) The method according to claim 1, characterized in that the mold occupies the supply section, the crystallization section and the cooling section at the same time. 3) A crystallization rate of 0.1 to 5 mm/min is maintained during the directional solidification of silicon.
or the method described in paragraph 2. 4) Claims 1 to 6, characterized in that in the crystallization section, a mold containing solidified silicon is rotated.
The method described in any one of paragraphs. 5) A patent claim characterized in that the solidified silicon is tempered to 900° to 1300°C at a cooling rate of 0.5° to 30°C/min, then rapidly cooled to a temperature of 700°C or less, and subsequently removed. The method according to any one of the ranges 1 to 4. 6) an evacuable, vacuum-tight casting containing a melting crucible from which silicon can be removed, surrounded by a heating device and separated from the outside air by a gate;
a casting station having at least one charging channel communicating with the melting crucible and a mold cradle for moving the mold to a casting position; an energy source for supplying energy to exposed silicon surfaces within the mold; at least one crystallization section connected to the casting section and having an energy removal device opposite the casting section; at least one feed section communicating with the casting section but separated from the casting section by a vacuum-tight isolation device; 1. A circulation device for silicon molded bodies, characterized in that it comprises a conveying means for moving the silicon molded bodies to a desired location; and gas supply and discharge pipes. 7) The apparatus according to claim 6, wherein the supply section is divided into an insertion section and a preheating section. 8) The apparatus according to claim 6 or 7, characterized in that the cooling section is divided into a tempering section and a quenching section. 9) The melting crucible, the rotary table-like mold holder in the lower surface, the crystallization part and the tempering part are charged and
Any one of claims 6 to 8, characterized in that the casting tower is disposed within a casting tower connected to a discharge line.
Equipment described in Section. 10) According to any one of claims 6 to 9, characterized in that several parts are provided to operate in parallel or sequentially for the most time-consuming process. The device described.